Needle operation device in high-speed sewing machines

ABSTRACT

A needle operation device in high-speed sewing machines comprising a crank integrally formed with a reciprocating shaft rotatably mounted in the machine frame of said sewing machine, an actuating arm mounted on said crank for rocking movement relative to the crank, a slide pivoted to one end of said actuating arm and having a sewing needle secured thereto and a mounting member adjustably secured to said machine frame and rotatably receiving a bearing therein, said bearing slidably receiving the other end of said actuating arm.

United States Patent Hirayarna Feb.29,1972

NEEDLE OPERATION DEVICE IN HIGH-SPEED SEWING MACHINES [72] Inventor: Tetsuro Hirayama, Tokyo, Japan [73] Assignee: Tokyo .luki Kogyo Kabushiki Kaisha,

Tokyo, Japan [22] Filed: Sept. 11, 1970 [2!] Appl. No.: 71,314

[52] U.S.Cl ..l12/221,74/l04 [51] Int. Cl. ..D05b 55/14 [58] FieldotSearch ..ll2/221,218R;74/l03, 104

[56] References Cited UNITED STATES PATENTS 2,799,236 7/1957 Marforio et al ..1 12/221 FOREIGN PATENTS OR APPLICATIONS 908,438 l0/1954 Germany ..l12/22l Primary Examiner-H. Hampton Hunter AttorneyWenderoth, Lind & Ponack [57] ABSTRACT A needle operation device in high-speed sewing machines comprising a crank integrally formed with a reciprocating shaft rotatably mounted in the machine frame of said sewing machine, an actuating arm mounted on said crank for rocking movement relative to the crank, a slide pivoted to one end of said actuating arm and having a sewing needle secured thereto and a mounting member adjustably secured to said machine frame and rotatably receiving a bearing therein, said bearing slidably receiving the other end of said actuating arm.

4 Claims, 7 Drawing Figures PATENIEDFEB29 i972 SHEET 1 [IF 3 a: Jam n H 'IETSURO HI RAYAMA INVENTOR dda/11K l M ATTORNEY s PATENTED FEB 2 9 I972 SHEET 2 [IF 3 TETSURO HIRAYAMA INVENTOR BY MAJ/112% ,ZZ aM/MTTORNEY s PATENTEDFEB 29 S972 SHEET 3 BF 3 TETSURO HIRAYAMA,

INVENTOR dlmaZL d GL/MATTQRNEY s NEEDLE OPERATION DEVICE IN HIGH-SPEED SEWING MACHINES BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a needle operation device in sewing machines and more particularly, to a needle operation device adapted to drive a sewing needle in a rectilinear path through a reciprocating drive movement imparting source.

2. Brief Description of Prior Art There have been proposed a variety of needle operation devices for sewing machines and one of such prior art needle operation devices has been disclosed in US. Pat. No. 2,799,236. However, when the needle operation device disclosed in the above-mentioned US. Pat. No. 2,799,236 is incorporated in an overlock sewing machine for obtaining a reciprocal up and down movement stroke on the order of 23 mm. for the sewing needle in the sewing machine, the reciprocating crank which serves as the driving source for the needle operation device must reciprocate covering an angle of about 50. Therefore, when the needle is driven at a high speed the inertia force of the crank and the like will be inevitably great. As a result, when the direction of movement of the needle is reversed while the needle is being driven at the high speed, the various components of the needle operation device will be inevitably subjected to a substantial load which accelerates abrasion on the components and causes the sewing machine to vibrate resulting in uneven seam formation. Accordingly, the conventional needle operation devices including the device of the above-mentioned U.S. Pat. can not be suitably employed in connection with high-speed sewing machines. In any of the conventional needle operation devices, if the curvilinear angle of the crank is reduced a desired and suitable reciprocal up and down stroke for the needle can not be obtained. If it is desired to obtain a desired and suitable stroke for the needle movement with the crank having a small curvilinear angle in rotation, the dimensions of links which connect between the needle and crank must be made two times larger than those of the corresponding components of the conventional needle operation devices while maintaining the dimensional ratio between the links unchanged and accordingly, the needle operation device will become massive. Therefore, in such an arrangement, while the curvilinear angle of the crank may be reduced to one-half that of the comparative corresponding component the length of the needle actuating arm will be inevitably increased resulting in increase of the mass of the actuating arm which produces the above-mentioned disadvantages as described in connection with the conventional needle operation devices when they are employed in connection with high-speed sewing machines.

Furthermore, in any of the conventional needle operation devices, when the sewing machine in which the needle operation device is incorporated is driven the long and massive rod, which supports one end of the needle-actuating arm which is adapted to impart reciprocal up and down movement to the needle, also rotates reciprocally, and accordingly, the inertia force of the rod will be increased as the sewing machine is driven at a high speed. As a result, when the direction of movement of the needle-actuating arm is reversed during the operation of the sewing machine the various components of the needle operation device will be subjected to a substantial load due to such increased inertia force which accelerates abrasion on the various components of the device. Such substantial load applied on the components in turn increases frictional resistance and causes seizure at one end of the rotating and rocking actuating arm where the arm is supported by the rod and the device will be rendered inoperative. Thus, such a needle operation device can not be suitably and effectively used in connection with high speed sewing machines.

Furthermore, in any of the conventional needle operation devices, it is impossible (or at least, very difficult) to obtain a rectilinear movement for the needle relative to the straight guide bar within a permissible range due to error or errors in the manufacture of the various components of the operation device and frictional resistance on the straight needle guide bar will be increased thereby to increase torque resulting in seizure, heat generation, abrasion and the like on the components of the operation device.

SUMMARY OF THE INVENTION The object of the present invention is to eliminate the above-mentioned disadvantages inherent in the conventional needle operation devices by providing a needle operation device which comprises a reciprocating crank having a fixed axis, a needle-actuating arm for reciprocally driving a needle in an approximately rectilinear path connected to said crank for bodily angular movement about one pivoted end thereof which is positioned on the side of said fixed axis of the crank opposite the side where the arm is connected to the crank, a slide supported by said pivoted end of the actuating arm for reciprocal up and down movement and having a needle secured thereto, said needle being guided in a fixed straight guide means which has an axis intersecting the axis of said arm at substantially right angles and a cylindrical bearing having a length sufficient for slidably receiving said second-mentioned end of the actuating arm and for bodily rocking the arm about a fixed axis which intersects the axis of the arm and the projection of the axis of said fixed guide means at substantially right angles.

The above and other objects and attendant advantages of the present invention will be more readily apparent to those skilled in the art from a reading of the following description referring to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevational view of a preferred embodiment of needle operation device according to the present invention;

FIG. 2 is a longitudinally sectional view taken along substantially the line ll-II of FIG. 1;

FIG. 3 is a cross-sectional view taken along substantially the line III-III of FIG. 1;

FIG. 4 is a view diagrammatically showing the operating principle of said needle operation device;

FIG. 5 is an exploded perspective view especially showing the needle-actuating arm-mounting member of said operation device;

FIG. 6 is a side elevational view of a modified embodiment of needle operation device according to the present invention which incorporates a modified actuating arm-mounting member therein; and

FIG. 7 is a longitudinally sectional view taken substantially along the line VII-VII of FIG. 6.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION The present invention will be now described referring to the accompanying drawings and more particularly, to FIGS. 1-3 and 5 thereof which show a first or preferred embodiment of the invention. The needle operation device generally comprises a reciprocating shaft 2 rotatably supported in the frame I of a sewing machine in which the needle operation device of the invention is incorporated and the shaft has one end extending outwardly of the machine frame and connected to a suitable conventional drive mechanism (not shown) through a suitable conventional transmission means (not shown) to be rotated thereby. The other end of the shaft 2 has a crank 4 integrally formed therewith and the crank in turn has an integral internally threaded crankshaft 3 which has an axis parallel to the axis of the rotary shaft 2. A rockable needle-actuating arm 7 having one bifurcated or U-shaped end 5 and the other end in the form of a slidable bar 6 is loosely supported at a point between the opposite ends on the crankshaft 3 by means of a washer 8 which prevents the arm 7 against slipping out of the crankshaft 3, but allows the arm to move relative to the crankshaft and a screw 9 which extends through the washer and is threaded into the internally threaded crankshaft 3. A mounting member 12 comprising a thinner or plate portion and an integral thicker or block portion is provided for slidably supporting the slidable bar 6 of the actuating arm 7 and the plate portion has a pair of aligned elongated slots 10 and 10 which have a common axis extending along the center of the rocking movement F-F (FIG. 4) of the actuating arm 7 and is adjustably secured to the machine frame 1 by means of setscrews l1 and 11 which extend through the respectively corresponding slots into the machine frame 1. The block portion of a mounting member 12 has a transverse center through opening 13 which has an axis intersecting the axis of the slidable bar 6 at right angles. A cylindrical bearing 14 which has an axis intersecting the axis of the slidable bar 6 at right angles is rotatably received in the center opening 13 of the block portion of the mounting member 12 and through which the slidable bar 6 extends loosely and transversely. The mounting member 12 has a pair of aligned openings 15 and 15' at the opposite ends, respectively, which communicate with the center opening 13 on the opposite sides thereof and through which the slidable bar 6 also loosely extends. The opposite legs of the bifurcated end 5 of the actuating arm 7 have aligned openings and loosely receive a substantially hollow slide therebetween and the slide is pivotally supported in the actuating arm 7 by means of a pivot pin 21 which extends through the slide and openings in the bifurcated end legs. The slide 20 has a through opening 17 which has an axis intersecting the axis of the actuating arm 7 and the extension of the axis of the reciprocating shaft 2 at right angles and the opening 17 slidably receives a guide bar 23 which has the upper end fix edly secured to a support member 22 which is in turn fixedly secured to the machine frame 1. The length of the center opening 13 is larger than that of the bearing 14 and the bearing is positioned nearer to the outer end than the inner end of the opening 13 leaving a space between the opening inner end and the adjacent end of bearing for the purpose to be described hereinbelow. The bearing 14 has a transverse opening for loosely receiving the slidable bar 6 of the actuating arm The outer side of the center opening 13 in the block portion of the mounting member 12 is covered by a cover plate 24 which is fixedly secured to the adjacent or outer side of the block portion by means of setscrews and disposed within the remaining space of the center opening 13 in the mounting member block portion which is defined by the adjacent or opposite sides of the machine frame 1 and bearing 14 is a circular retaining member 26 which is fixedly held in position by means of setscrews which are in turn threaded into the opposite ends of the mounting member block portion whereby the bearing 14 is allowed to rotate about its own axis, but is prevented from moving axially within the center opening 13. The machine frame 1 is provided with an opening 27 extending through transversely of the machine frame in axial alignment with the center opening 13 in the mounting member block portion.

FIGS. 6 and 7 illustrate a modification of the mounting member 12 as shown in FIGS. 1 through 3 and 5. The modified mounting member 34 generally comprises a hollow cylindrical bearing 30 fixedly secured in the machine frame 1 and a circular cross section core 31 loosely received in the bearing and having an enlarged head portion 35. The shank of the core 31 is internally threaded. A washer and screw arrangement 32 and 33 is provided for allowing the core 31 to freely rotate within the bearing 30, but for preventing the core from slipping out of the bearing. The head portion 35 of the core 31 is provided with an opening 36 extending through transversely of the head portion for slidably receiving the slidable bar 6 of the needle-actuating arm 7. Thus, in the embodiment of FIGS. 6 and 7, when the reciprocating shaft 2 having a fixed axis is reciprocated from the solid-line position shown in FIG. 4 in the counterclock direction, the slidable bar 6 of the actuating arm 7 is caused to slidably move within the opening 36 in the core head portion which in turn rotates the core 31.

In both the .embodiment shown in FIGS. 1-3 and 5 and that shown in FIGS. 6 and 7, the relationship between the dimensions of the various components thereof are selected in the following way. Referring to FIG. 4 of the accompanying drawings, the distance from the axis of the bearing 14 to that of the pivot pin 21 which is represented by B is 2.88 inches, the distance from the axis of the bearing 14 to that of the reciprocating shaft 2 which is represented by C is 1.95 inches, the length of the crank 4 or the distance from the axis of the reciprocating shaft 2 to that of the crankshaft 3 as represented by D where the crank 4 and actuating arm 7 are connected together is 0.807 inch and the distance from the axis of the crankshaft 3 where the actuating arm 7 and crank 4 are connected together to the axis of the pivot pin 21 where the actuating arm 7 and slide 20 are connected together is 1.74 inches which is represented by E. When the reciprocating shaft 2 is rotated by about 28 (shown by a in FIG. 4) from the position in FIG. 1 in which the axes of the bearing 14, crankshaft 3, reciprocating shaft 2 and pivot pin 21 align in a common plane, the crank 4 is caused to rock about l4 above and below the above-mentioned plane, respectively whereby the slidable bar 6 rotates the bearing 14 about its axis as the bar 6 slides within the transverse opening in the bearing 14. This causes the actuating arm 7 to drive the slide 20 up and down along the guide bar 23 by means of the pivot pin 21 which extends across the bifurcated end 5 of the actuating arm 7. The up and down movement of the slide 20 in turn causes a needle 19, which is secured to the lower grip portion 18 of the slide by means of a setscrew (not shown), to move up and down in an approximately rectilinear path. When the reciprocating shaft 2 is rotated about 28, the needle 19 moves up and down in the stroke of about 0.945 inch. In the embodiment as shown in FIGS. 1 through 3 and 5 with the abovementioned relationship between the dimensions of the various components, the deviation of the needle 19 with respect to the rectilinear plane along the guide bar 23 is about 3.94Xl5 inch as the needle 19 moves in the stroke of 0.945 inch.

The operation of the needle-operation device of the present invention will be now described. When the reciprocating shaft 2 having the fixed axis is reciprocated from the solid-line position in FIG. 4 in the counterclock direction, the crank 4 is also reciprocated in the counterclock direction about the axis of the shaft 2 and the crankshaft 3 integrally formed with the crankshaft 4 is rotated about the reciprocating shaft 2 describing a circle having the radius of D whereby the actuating arm 7 is rotated so as to rotate the bearing 14 in the clockwise direction with the bar 6 of the arm 7 sliding leftwardly within the bearing 14 by a small distance and then the arm rotates in clockwise direction about the bearing 14. Thus, the pivot pin 21 at the bifurcated end 5 of the actuating arm 7 descends describing a substantially rectilinear line substantially parallel to the axis of the guide bar 23 having the fixed axis. As a result, the slide 20 descends along the guide bar 23 and the needle 19 which is secured to the lower gripping portion 18 of the slide 20 also descends.

As the reciprocating shaft 2 is rotated in the manner mentioned above, the axis of the crankshaft 3 is positioned in the plane F-F (FIG. 4) which aligns with the axes of the bearing 14 and shaft 2. Thereafter, when the shaft 2 is further rotated in the counterclockwise direction, the slidable bar 6 of the actuating arm 7 rotates in the clockwise direction about the bearing 14 by a small angular distance while the bar 6 is moving rightwardly by a small distance within the bearing 14 and then the actuating arm 7 further rotates in the clockwise direction about the bearing 14 whereby the pivot pin 21 at the bifurcated end 5 of the actuating arm 7 descends describing a substantially rectilinear line substantially parallel to the axis of the guide bar 23 and the needle 19 also descends by means of the lower grip portion 18 which descends together with the slide 20. As a result, the various components of the needleoperation device of the invention will assume the position as shown by the chain and dotted line in FIG. 4 whereupon the downward movement of the needle 19 covering the distance of A comes to end.

In order to raise the needle 19 in a next cycle of operation, the reciprocating shaft 2 is rotated in the clockwise direction from the position of the chain and dotted line of the various components in FIG. 4. The rotation of the shaft 2 rotates or slides the various components in the directions opposite to the previous directions in which they rotated or slided as the shaft 2 reciprocated in the previous counterclockwise direction. Thus, the needle 19 is raised or returned to the solid line position of FIG. 4. Therefore, it will be understood that as the shaft 2 reciprocates by the angle a (28 in the illustrated embodiments of the present invention), the needle 19 reciprocates up and down by the distance of A (0.945 inch in the illustrated embodiments of the invention) in a substantially rectilinear path.

And if there are variations in the factors such as B, C, D and E due to error or errors in the manufacture of the various components, the slide 20 would slide in a substantially rectilinear plane in excess of a permissible error for the slidable fitting between the slide opening 17 and the guide bar 23 resulting in generation of any excessive torque in the sewing machine wherein the novel needle operation device is incorporated. When such a phenomenon occurs, according to the present invention, the setscrews 11 and 11 which secure the mounting member 12 to the machine frame 1 are loosened and the mounting member 12 is moved along and relative to the machine frame 1 by means of the adjusting slots and 10 thereby to change the distance B between the axis of the bearing 14 and that of the pivot pin (FIG. 4). Such adjustment also changes the distance C between the axis of the bearing 14 and that of the reciprocating shaft 2 (FIG. 4). Therefore, the up and down movement of the slide 20in an approximately rectilinear path can be always maintained within a permissible error without causing any excessive friction between the opening 17 in the slide 20 and the guide bar 23.

In the novel sewing needle operation device as mentioned hereinabove, since one end or bifurcated end 5 of the needleactuating arm 7 is connected to the slide 20 which is loosely fitted on the straight guide bar 23 and has the needle 19 secured thereto while the other end of the actuating arm 7 which is in the form of the slide bar 6 is slidably received in the bearing 14 which is in turn rotatably received in the center opening 13 in the block portion of the mounting member 12, when the crank 4 reciprocates the reciprocation of the crank is transmitted through the actuating arm 7 to the needle 19 whereby the needle is caused to move in an approximately or substantially rectilinear path. Thus, it will be appreciated that in order to obtain substantially the same amount of stroke for the sewing needle the novel needle operation device may have substantially the same dimensions as any conventional comparative needle-operation device and that the rotation angle of the crank 4 (or reciprocating shaft 2) necessary for moving the needle 19 up and down may be only one-half that of the corresponding component in the conventional comparative needle-operation device. Therefore, since the inertia force of the crank and the like in the novel needle operation device is smaller than that of the corresponding component of the conventional comparative needle-operation device, when the rotation direction of the crank is reversed during the operation of the sewing machine the various components of the needle-operation device are subjected to less load whereby abrasion on and vibration of the various components, which are great in the conventional needle-operation device, are substantially decreased resulting in decrease in rotation torque. Furthermore, since the bar 6 at one end of the actuating arm 7 is slidably received in the opening in the bearing 14 and the bearing is in turn reciprocally rotated as the actuating arm is reciprocally rotated and has a relatively small mass whereby the force of rotation inertia of the bearing 14 caused by the rotation of the actuating arm 7 is greatly reduced, the novel needle-operation device attains great improvement in performance. In addition, there are many other advantages such as prevention of seizure of the slidable bar 6, attainment of higher-speed operation of the sewing machine, prolonged service life of the sewing machine, constant and even seam-forming performance and so on.

And any deviation of the slide 20 from a permissible rectilinear movement range due to variations in the dimensions of the various components of the needle operation device caused by errors in the manufacture of the components can be controlled within the permissible range by changing the securing position of the mounting member 12 relative to the machine frame 1 and accordingly, a suitable telescopic fitting relation can be obtained between the opening 17 in the slide 20 and guide bar 23. As a result, the novel needle-operation device generates only a small amount of torque in the sewing machine in which the needle-operation device is incorporated and effectively prevents rattling of the various components of the needle-operation device due to seizure, heating and abrasion of the various components of the needle-operation device. Furthermore, the various components of the needleoperation device can be easily processed and assembled and the needle-operation device comprising such components is simple and reliable in operation.

Finally, it is to be understood that various alterations, modifications and/or additions may be introduced into the preferred embodiments and arrangements of parts previously described, without departing from the scope and spirit of the invention.

What is claimed is:

1. A needle-operation device for sewing machines comprising a reciprocating shaft having a fixed axis, a crank having one end integrally formed with said shaft for reciprocation about said fixed axis, a needle-actuating arm rotatably supported on the other end of said crank for bodily arcuate rocking movement about one end positioned on the side of said fixed axis opposite to the side on which said crank is supported by said shaft, a straight guide means adjacent said one end, a slide pivoted to said one end of the actuating arm for movement along said straight guide means and supporting a sewing needle for reciprocal movement in an approximately rectilinear path and a mounting member for said needle-actuating arm supporting the other end of the actuating arm for reciprocal movement along the axis of the arm and having a bearing rotatable about a fixed axis which intersects the axis of said arm and the projection of the axis of said fixed guide means at right angles.

2. A needle operation device for sewing machines comprising a frame, a reciprocating shaft reciprocatably supported in said frame, a crank having one end integrally formed with said shaft for reciprocation about the axis of the shaft, a needle actuating arm rotatably supported on the other end of said crank for bodily arcuate rocking movement about one end positioned on the side of said shaft axis opposite the side on which said crank is supported by said shaft, a straight guide means adjacent said one end, a slide pivoted to said one end of the actuating arm for movement along said straight guide means and supporting a sewing needle for reciprocal movement in an approximately rectilinear path and a mounting member for supporting said needle-actuating arm and having slots by means of which the mounting member is secured to said frame, said mounting member having a bearing rotatable about a fixed axis which intersects the axis of said arm and the projection of the axis of said fixed guide means at right angles.

3. A needle operation device for sewing machines as set forth in claim 2, in which said slots in the mounting member by means of which the mounting member is secured to said frame extend along the length of the mounting member so that the mounting member may be adjusted along a bisector of the rocking movement angle of said needle actuating arm.

4. A needle operation device for sewing machines as set forth in claim 3, in which said rocking movement angle of the needle actuating arm is 28. 

1. A needle-operation device for sewing machines comprising a reciprocating shaft having a fixed axis, a crank having one end integrally formed with said shaft for reciprocation about said fixed axis, a needle-actuating arm rotatably supported on the other end of said crank for bodily arcuate rocking movement about one end positioned on the side of said fixed axis opposite to the side on which said crank is suppoRted by said shaft, a straight guide means adjacent said one end, a slide pivoted to said one end of the actuating arm for movement along said straight guide means and supporting a sewing needle for reciprocal movement in an approximately rectilinear path and a mounting member for said needle-actuating arm supporting the other end of the actuating arm for reciprocal movement along the axis of the arm and having a bearing rotatable about a fixed axis which intersects the axis of said arm and the projection of the axis of said fixed guide means at right angles.
 2. A needle operation device for sewing machines comprising a frame, a reciprocating shaft reciprocatably supported in said frame, a crank having one end integrally formed with said shaft for reciprocation about the axis of the shaft, a needle actuating arm rotatably supported on the other end of said crank for bodily arcuate rocking movement about one end positioned on the side of said shaft axis opposite the side on which said crank is supported by said shaft, a straight guide means adjacent said one end, a slide pivoted to said one end of the actuating arm for movement along said straight guide means and supporting a sewing needle for reciprocal movement in an approximately rectilinear path and a mounting member for supporting said needle-actuating arm and having slots by means of which the mounting member is secured to said frame, said mounting member having a bearing rotatable about a fixed axis which intersects the axis of said arm and the projection of the axis of said fixed guide means at right angles.
 3. A needle operation device for sewing machines as set forth in claim 2, in which said slots in the mounting member by means of which the mounting member is secured to said frame extend along the length of the mounting member so that the mounting member may be adjusted along a bisector of the rocking movement angle of said needle actuating arm.
 4. A needle operation device for sewing machines as set forth in claim 3, in which said rocking movement angle of the needle actuating arm is 28*. 